Which of the following macromolecules :n1o(erv( 7 zu+;+znafskorm;1sajjl( n4 j ydescribe a typical enzyme?

  What type of reaction is photosynthesgw mo-p4t2 k4gis?

  What is the substrate for the enzyme laq;+*fjbc;iws:k o7wk, r5od jctase?

  Which of the following /adn21btm* unstages of cellular respiration takes place in the cytopla* n an1m/ubd2tsm?

  Which of the following would not be useful in determining the rate of an enz:/e pqdp1xzn.nriz: 3yme-car:n i 3ndzq.pz:p1 xe/talyzed reaction?

  Which of the following procbpzi 1/5rg4 twesses may be described as catabolism?

  Which of the following statements is bqh8;rbnz3w vbj. 8 bfo*t..au est depicted by the figure below?

  Which statement about enzymes l 1w.lem:6(hb4u fy:qlkx. xjis not true?

  Which of the following graphs best(m ,ysve y)2,*t j,nid/lfzrk illustrates the relationship between temperature and the acy*ivm, y (jsr tenzkdlf2/,, )tivity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentratiwduh0so;. +s h5 r-lu5vb4k fqons of substrate affect enzyme acubk5q0d5l;-whs+rus o.4 fv htivity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A diagram outlining;4r yhd;,:yrkx czr-s the Calvin cycle is s4k-r: dhy;rrcz,;yx shown below.

The image below shows the catalytic site of an enzyme. The substrate is shown inmu1; gwa d0.byzz-: y1aa5b5v*fea ad black and i 1:5yamv .dz; uag0*fb5y1e-bdazawa s bound to the active site.





1.State how the activation energy is changed by adding an enzyme to a reaction.
2.Distinguish between anabolic and catabolic pathways.

  Which are correct descripti4sdeo+dcz s 7jji6h c4 f9baf6+ p,em:ons of the enzyme catalysed metabolic pathways shown below? Letters represen+e 9s 4dj+ s4fmb fi7zjd h:6oc,6epcat various products of individual reactions.

  Which of the following describes the role of inhibitors in enzyme-catalysed reikut/ s-rywio4 o+1q 3actions?u3oq iotri+ k s4-/y1w

  Which of the following correctly describes photosynthesis or respiratiowsn uxjx 3kww.v:9dw w18sm1,n?

Many enzymatic reactions happen as pathways involving multiple step6qi4acyw ,pm(v: 1 : b1niierxs and multiple enzb:6 amxvirqewcp1i (in1y4:, ymes.

1.Describe how enzymes catalyze reactions.
2.Outline the advantages of enzyme-substrate specificity.

  Which of the following best describes the inhibitarzg:g wht)cl o60*t6or in the image below?

  Which of the following statements are true regarding regulation by end-product j om7 ca.:q:to,d8zkz inhibiti7d 8, jck.mzz:tqa:o oon?
I. The end product binds to the allosteric site of the enzyme.
II. The binding of the end product is reversible.
III.End product inhibition is an example of negative feedback regulation.

  The following image shows the structlvnji5*)5 cydg f)0auure of the lysozyme enzyme. The darkened structure in black is the substrate and is gcyjn)55ui * )df0 valbound at the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be used to study the effect 3,2nxg tdkas m 4his28w9it/p of temperature on the activity of the enzyme amylase. 3i2 sh isttpd kg8,249/xwnma



1.Outline how this equipment could be used to set up a study into the effect of temperature on amylase activity, up to the point of getting the results.
2.Outline how the rate of reaction of the breakdown of starch by amylase could be measured using the equipment given.
3.Describe a suitable control experiment for this study.
4.Suggest one way to increase the reliability of the data that can be gathered from this experiment.
5.Using the axis below draw a graph of the expected results from the study in part (a).

  Which of the following statements describes how enzymes intq i4i/bkhg grb6r54j0eract with substrates to catalyze react4 5/jrqbg bhrg60kii 4ions?
I. Enzymes and substrates in solutions collide with one another, and the substrate is bound at the active site.
II. There is more movement of the substrate in a reaction because the substrate is usually smaller than the enzyme in size.
III.When the substrate binds to the active site, the shape of the enzyme changes slightly so it can accommodate the substrate.

Outline two ways enzyme catalysed reactdtgdjaz 714 ttt5t2-ou . i+ 6p;raztlions can be measured.

  How does denaturation change the properties of an 84xjz gci d*ng1 w 0qbyu9*w,oatey47enzyme?

  Enzymes play a role in catalysing reactions. Which of the followipb y)y+ -ypo. cazzlaj/bs:3) ng statements are tr cb:yaz3s ay+ j.b)yo-pl/zp)ue?
I.The substrate is temporarily provided with energy before being converted to a product.
II. Enzymes reduce the activation energy needed for the reaction.
III.The active site binds to the substrate making it easier for bonds to be broken or formed.

  What is a characteristic thatv; gz;od0j8yn separates mammals or endotherms from ectotherms that have fluctuating body temperaturesg;dj 0zv n;oy8?

  A metabolic pathway that converts threonine to the end-product d)slx*)c mqv,isoleucine consists of five reactions. Threonine is converted )lcvxd, sm*)q to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in the pathway.
In the following diagram, the enzymes have been labelled as E1, E2, E3, E4 and E5.


Which of the following shows how this pathway is regulated?

  The graph shows the effect of increasing pH on the rate of annf :qo474fzqeq .*dtc enzymatic reaction. What is occurring d 4ff.7qden c:*zq 4toquring the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentration on an enzymatixfbyyygi;39 qz6:5mic reaction. What could bi3qfm6y9y;g 5bxz iy: e the independent and dependent variables in this experiment?

  The diagram shows the pathway that converts threon/t) ),laaqf4svdxraa v5lz ;,ine to isoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was imm,hu: ag4q:ojijk zl0lfmd6z*rc r98 4obilized on a matrix and its activity was compared with thatig8cmd:fk qu4ja0 j:4rozr, z96l *lh of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axis).



Which of the following statements is true?
I. Both soluble and immobilized enzymes are inactive at higher pH values of 8.
II. The immobilized Enz A is more resistant to pH changes showing more activity than the soluble enzyme at most tested pH values.
III. Immobilizing Enz A did not decrease its catalytic activity.

  Purified enzymes are ekbj) *0 (f l zv44mjut x42g-va9qfgwrasily denatured. Which of the following is the best way to kvk *gm9j4g)4t2fvj0 z u xf-wla 4r(qbeep enzymes active for a longer period of time?

  Which of the following describes some types of extracellula289qrn,po3zq:z,xma s he s z.r enzymes?

  The enzyme pepsin hydrolyses proteins to releasei:4c.zj4 rjmh* 6bfn k peptides in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a cok4m 4h. in *rjzcj:bf6nstant temperature of $30{\circ}C.

1.Describe the trends shown by the graph.
2. 1.Outline why it is important that temperature is kept constant in this experiment.
2.State one factor other than temperature that would need to be controlled in this experiment.
3.Suggest a method that can be used to maintain a constant temperature in this experiment.
3.Calculate the rate of reaction during the first 4 minutes when the enzyme pepsin is exposed to 5 mM of protein. Make sure you show your working. ----待选择----+-   
4.Explain the observed results.

  The graph below shows the rate of reaction of an enzyme with increasing subs0*z dau4hrg9 rtrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and 9*u 0haz4drr gthe activity was monitored for each of the reactions. The curve marked A coincides with the activity of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme ad57x2rkoq 3j kctivity, a student cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, 3jr7 xk2 od5kqadded 50 ml water and used a blender to homogenize the turnip root. The homogenate was filtered and the liquid extract was stored in a test tube at room temperature.


The turnip extract and water were added to the conical flask first. Then 3% hydrogen peroxide solution was added to the conical flask, as shown in the image above. The oxygen produced is collected over 1 minute and measured in an inverted measuring cylinder, as shown.
The student wanted to conduct an experiment to see the effect of increasing enzyme concentration on the reaction. She made up the different concentrations as shown in the table below and added 1 ml of 3% hydrogen peroxide to each.

1.Suggest why the process of grinding the turnip root and extracting the filtrate was carried out.
2.State the dependent variable.
3.Explain why the volume of water was varied, as shown.
The following graph was obtained when the student varied the substrate (hydrogen peroxide) concentration, keeping the enzyme concentration constant.



4.From the graph shown above, calculate the percentage increase in volume of oxygen gas produced when using 1% hydrogen peroxide compared to 0.5% hydrogen peroxide.  %
5.Outline the reasons for the shape of the curve obtained.
The student repeated the same experiment but added an inhibitor along with the enzyme to the reaction mix. She got the following results.


6.Deduce, with an explanation, whether a competitive or non-competitive inhibitor was used in the investigation.
7.Other than the factors already mentioned, state one other factor that can lower the rate of an enzyme controlled reaction.

  The mevalonate pathway is shown below. Inhibitors to w pe5:e3kyqia:l8ro, the enzyme HMG- CoA reductase can lower the production of ch,k opwi:r85eaq3: ely olesterol.


Statins lower cholesterol, reduce the risk of heart attacks, and prevent strokes. They are known to inhibit HMG-CoA reductase, which is the rate-limiting enzyme of cholesterol biosynthesis in the mevalonate pathway (image above).
Which of the following describes the mechanism of action of statins in lowering cholesterol?

  Which of the following are involved in denaturles l:xovkh0*2zjr8 +ation?
I.A change to the three dimensional structure of the protein
II. A change in the amino acid sequence of the protein
III. Changes in the properties of the protein

  Students were investigati;2xor*dl -t5md tpvv:ng metabolic reactions in the classroom and were given an experiment which demonstrated the eff- lm*pro: dv2tv5d;x tect of temperature on a catabolic reaction.
A sample of fat was added to a beaker, which contained 150ml of a 1% sodium chloride solution.


The beaker and its contents were then added to a water bath, which was set at 15
o
C. The beaker was given 5 minutes to equalise with the temperature of the water bath. After 5 minutes, 5 ml of a 2 % lipase solution, at the same temperature as the water bath, was added to the beaker.


5 ml of 2 % sodium hydroxide (NaOH), pH 8.4, was added to a test tube and phenolphthalein, a colourless solution which turns pink in basic environments, was then added. The intensity of the pink colour is proportionate to the strength of the basic solution.
At exactly 20 minutes, a 5ml sample was taken from the beaker incubated in the water bath and added to the test tube.

The contents of the test tube were then immediately transferred into a cuvette and placed in a spectrophotometer set at 420 nm. The percentage transmission of light able to pass through the sample was measured and recorded.

The procedure was then repeated using water baths set at a range of different temperatures. The measurements were recorded in a table and presented in a graph.



1. 1.State the independent variable in this experiment.
2.Identify two factors, not already mentioned, that would need to be controlled in this experiment
2. 1.Explain how the spectrophotometer is able to measure the breakdown of fat.
2.Explain the effect of increasing the temperature from 15
o
C to 35
o
C on the rate of the catabolic reaction.
3.Predict the percentage transmission for a sample incubated at 20
o
C.  %
4.Evaluate the claim that based on the data, the optimum temperature for lipase activity is 35
o
C.

  In an experiment, the effect of increasing y1dz)wihm2 t*q(u z3ukj. jb 1temperature on the efficiency of lactase activity is tested. Whi i3buqzt dk()m .*hw1jzyj u21ch is an appropriate dependent variable for this experiment?

  A study has been conducted8p;z;e ;mybm 20gujgv i e.e.e on the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-free mpi;me; ye g mu..2ez;0jeb8gvilk.



1.Deduce which temperature used in this experiment was the optimum one for the enzyme Bg10. Give a reason for your answer.
2.Explain the change in enzyme activity at temperatures above $40^{\circ}C$.
3.Evaluate whether the data supports the claim that the optimum pH for the lactase enzyme Bg10 is 7.

4.Calculate the percentage difference in relative activity of the enzyme Bg10 when treated with 500 mM of glucose compared to 50 mM of glucose. Make sure you show your working.  %

Further studies have been conducted on other lactase enzymes to test their thermal stability at an optimum temperature of 60°C, when they are immobilised on graphene nanosheets, in comparison to lactase enzymes floating freely in milk.

5.Compare the trend shown by the immobilised enzyme to that of the soluble enzyme.
6.Calculate the range of data for the soluble enzyme over 10 minutes.  log %

The storage stability at room temperature of the immobilised enzymes has also been compared to lactase enzymes floating freely in milk.


7.Compare and contrast the storage stability of the immobilised and free soluble enzyme.

The reusability of the immobilised enzyme was tested, by analysing the activity of the immobilised enzyme over 10 uses.


8.State one advantage of being able to reuse immobilised enzymes.
9.Using the data provided, and your own knowledge, suggest why immobilised enzymes should be used to make lactose free milk.

1.There is a continuous need to find new drugsv h8q( 2idhvn- for treating patients with malaria. Describe how anti-malarial drugs are being discovered wi2h(nd-8 qvih vth new technologies.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.

1.Explain how increasing the concentration of an enz t qzpob7ao k* ob8bune3,6/n.(wb/cbyme affects the rate of reac36 w/ cbt( b 87,.bq*zanbeo/konbopu tion.
2.Lactase converts lactose to glucose and galactose. Outline how lactase is used in the food industry.
3.Discuss the industrial use of immobilized enzymes using a named example.

  Biomolecules can be broken down or synthesized tecsx6 lhp -0 wp;gt5h0hrough metabolic reactions. Which type(s) of metabolic reactions are condensationce;0lp6 w g px05shht- reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enz ,x(rq ;:mtm:w u c951pp6-chtpw mktdyme catalyzed reactions can be measured. pmu, : m6p:pw1mq -ttkctcd 9rhw(x5;
2.Draw a graph to show the effect of temperature on the reaction rate of an enzyme.


3.State how the optimum temperature can be determined using the graph drawn in part b.

1.Compare and contrast intracellular and extracellulsrtmul0)( be4v40lv rar chemical reactions, given one)40vlv rel br0tmu( 4s example of each type of reaction.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.